Cutting head for earth augers



SePf- 7, 1954 R. M. BIRDwELL CUTTING HEAD FOR EARTH AUGERS 2 Sheets-Sheet l .Filed Aug. 3, 1951 (l IN Robert M. Birdwe/l INVENTOR.

Sept 7 1954 R. M. BIRDWELL 2,688,465

CUTTING HEAD;.,F0R EARTH AUGERS Filed Aug. 5, 1951 2 Snets-Sheet 2 Raber M. Birdwell IN V EN TOR.

Attorney:

Patented Sept. 7, 1954 UNITED STATS PATENT :OFFICE 2,688,465 CUTTING HEAD FOR EARTH AUGERS Robert M. Birdwell, lWoodville, Tex.

Application August 3, 1951, Serial No. 240,232

1 Claim. 1

The present invention relates to new and useful improvements in earth boring apparatus and more particularly to an improved cutting head for earth augers for boring under highways, roadbeds or the like for laying pipe lines without disturbing or weakening the surface.

An important object of the invention is to provide a cutting head for earth augers which works inside the front end of the pipe to be laid whereby the pipe may be advanced with the advance of the auger.

Another object is to provide retractible cutters carried by a rotatable cutting ring arranged to swing radially outwardly of the ring into cutting position by centrifugal action andvto swing inwardly of the ring when the cutting head is stationary to enable the head to be pulled rearwardly and removed from the pipe.

A further object is to provide a device of this character of simple and practical construction, which is ecient and reliable in operation, relatively inexpensive to manufacture and otherwise well adapted for the purposes for which the same is intended.

Other objects and advantages reside in the details of construction and operation as more fully hereinafter described and claimed, reference being had to the accompanying drawings forming part hereof, wherein like numerals refer to like partsthroughout, and in which:

Figure 1 is a side elevational view showing the auger in a pipe in boring position;

Figure 2 is an enlarged side elevational view;

Figure 3 is a front elevational view;

Figure 4 is an enlarged sectional view of one of the stationary cutters taken on a line ll--ll of Figure 3;

Figure 5 is a transverse sectional view taken on a line 5-5 of Figure 3; and,

Figure 6 is a perspective view of one of the retractible cutters.

Referring now to the drawings in detail, wherein for the purpose of illustration I have disclosed a preferred embodiment of my invention, the numeral 5 designates the cutting head generally and which comprises a ring S having a bevelled cutting front edge I A spider 8 is secured inside ring E and is composed of crossed bars 9 and Ill welded to the ring and also welded to each other. A pilot auger I I is welded at its base to the crossed bars at the center of the ring and projects outwardly therefrom at its bevelled front edge l. A socket I2 is welded to the rear surface of crossed bars 9 and I0 and is formed with a hexagonal bore to receive (Cl. Z55-20) 2 a complementary shaped end on a drive shaft I4 which is secured in the socket by screws or other fasteners I5.

A group of stationary cutters I6 have their rear ends I'I inserted and welded in recesses I8 in one end portion of cross bar 9 adjacent one edge thereof and with the cutting front ends I9 of the cutters inclined in the direction of rotation ofthe ring and a second group of stationary cutters 2Q are similarly secured to the other end portion of the bar 9 adjacent its opposite edge and are also inclined in the direction of rotation of the ring, both groups of stationary cutters projecting forwardly of the bevelled front edge 1.

Pairs of spaced parallel apertured ears 2I are welded to the inside of ring 6 preferably at 90 with respect to each other, and a pin 22 is secured in each pair of ears to pivotally support an arcuate cutter 23 for radial swinging movement rearwardly and outwardly through notches 24 at the bevelled front edge of the ring to project beyond the periphery thereof. In their outward position the cutters 23 rest against the ring, as shown by full lines in Figure 5, and stops 25 are formed on the cutters 23 to engage the inside of the ring and hold the cutters in a retracted inward position, as shown by dotted lines, within the perimeter of the ring. Cutters 23 are set at a predetermined pitch to form a bevelled cutting edge 23a; at the leading outer corner thereof and also at a pitch to pull bored material rearwardly.

In the operation of the device, drive shaft I4 is coupled to a motor 2E and the cutting head placed in a pipe 21 to be laid under a roadbed 28 and having an internal diameter substantially equal to that of ring 6 so that the cutting head may rotate in the pipe.

The cutting head is moved to the front end of the pipe and as the head is rotated the pivoted cutters 23 will swing outwardly by centrifugal force beyond the perimeter of the pipe to bore through the earth. The pipe is advanced as the cutting head advances until the pipe completely underlies the roadbed. Stationary cutters I6 and 20 also pull loose dirt rearwardly through pipe 21 for removal at the rear end of the latter.

The cutting head may be withdrawn from the pipe at any time by cutting off the power and pulling the shaft rearwardly which causes the arcuate cutters 23 to strike the front end of pipe 2l and swing the cutters inwardly out of interference with the rearward movement of the cutting head.

In view of the foregoing description taken in conjunction with the accompanying drawings it is believed that a clear understanding of the device will be quite apparent to those skilled in this art. A more detailed description is accordingly deemed unnecessary.

It is to be understood, however, that even though there is herein shown and described a preferred embodiment of the invention the same is susceptible to certain changes fully comprehended by the spirit of the invention as herein described and the scope of the appended claim.

Having described my invention, what is claimed as new is:

In an earth boring apparatus, a cutting head comprising a ring, a spider in the ring and having recesses in the forward surface of the spider, a drive shaft connected to the spider and extending rearwardly from the ring, a pilot auger carried by the spider centrally of the ring and projecting forwardly thereof, stationary cutters carried by the spider and having rear end portions secured in said recesses and having front end portions inclined in the direction of rotation of the ring to feed earth rearwardly through the ring, and cutter blades pivoted at one end to the ring internally of the latter and with the free ends of the blades supported by the ring in a forwardly projecting position and adapted to swing radially outwardly beyond the perimeter of the ring by centrifugal action.

References Cited in the le of this patent UNITED STATES PATENTS Number Name Date 1,317,192 Jones Sept. 30, 1919 1,667,155 Higdon Apr. 24, 1928 1,881,101 Spaulding Oct. 4, 1932 2,234,451 Ransome Mar. 11, 1941 2,320,612 Kandle June 1, 1943 

